Technical Field
The invention relates to providing wireless coverage within a local area network. More specifically the invention is directed to providing multiple hotspots providing effective area coverage within a wireless local area network with the hotspots spatially separated, but operating simultaneously.
Description of the Background Art
Communications via power lines has been known from early in the 20th century. Due to its higher costs and other limitations for extending connectivity, the use of power line communication (PLC) systems has been limited to local area networks (LANs) within homes or offices or, at best, within apartment complexes. PLC has also found a limited number of applications where other types of communication methods do not provide the security and remote connectivity, such as for power line control applications. Basic devices for connecting to the power line for communication and power supply have been designed and used to provide service within LANs. Due to more efficient competing technologies, the infrastructure for PLC never developed to make it a mainstream technology. As a result, more advanced devices for communication using the PLC technology also were never developed.
It is advantageous to identify applications where PLC technology can be optimally used and to develop devices and systems to cater to such applications. One such application that is emerging is providing effective wireless coverage within a local area (wireless LAN area) such as an office, home, small business location, etc. using multiple wireless hotspot sensor (WHS) devices simultaneously.
One problem of having multiple WHS devices or units operating using the same frequency in proximity to each other is interference and fading within the coverage area due to signal overlap from the transmitted signals from multiple WHS devices. Multiple WHS devices become necessary when the wireless LAN area that needs to be covered by wireless connectivity exceeds the capability of a single WHS device.
Prior art technology uses transmitters with different frequencies to eliminate interference when multiple WHS devices have to be provided adjacent to each other within a wireless LAN to have wireless coverage of the wireless LAN area. FIG. 1 is a pictorial depiction 100 of prior art. The data from a data store 101 is modulated in the modulators 102, 103, and 104, each using a different frequency. The modulated frequency is impressed over the same transmission medium and sent through the cloud 105. The transmitted modulated data is received and separated into the three frequencies using the filters 120, 121, and 122. The data is transmitted by the adjacent WHS devices 123, 124, and 125, each using a different frequency. In this case adjacent WHS devices operate at different frequencies covering the three adjacent rooms 110, 111, and 112. The adjacent sensor devices 123, 124, and 125 are designed to have differing frequencies that do not interfere with each other even though the sensors are close to each other. With the transmitted power lobes 126, 127, and 128 overlapping at regions 130 and 131, if a single frequency spectrum is used for transmission of data by the sensors, then fading and interference in will occur in the regions of overlap 130 and 131, limiting the coverage provided. Though sensors with multiple frequencies is an elegant solution to the interference and fading problem when covering a LAN covering a large area, the use of multiple frequencies requires transmitters, filters, and sensors for each distinct frequency used by sensors that are adjacent to each other. This is an expensive solution. However, this is the only solution available today where multiple hotspots are needed to cover large areas within a wireless LAN because it is not feasible to cover the area with a single WHS unit.